In EDM, it is customary to provide a minute machining gap between a tool electrode and a workpiece, one or both of which are immersed in a machining fluid. Typically, under such conditions, the machining fluid is flushed through one or more openings provided in either or both of the tool electrode and the workpiece. It is, of course, possible that no such opening may be provided and "flushing" of the machining fluid into the machining gap can be effected periodically by reciprocating the tool electrode or the workpiece. Additionally, it is quite common in practice to utilize a plurality of fluid jetting nozzles directed toward the machining gap to guide introduce into the region of the latter the machining fluid at a relatively high velocity. A series of electrical discharges are created across the fluid-filled machining gap to remove material from the workpiece, thereby imparting to the latter a desired shape in accordance with a shape of the tool electrode.
When, however, these shapes contain irregular curvatures or involve a deep boring or slitting and thus present intricate two-dimensional or three-dimensional forming, the removal of machining chips, tar and gases accumulated at one or more of these portions becomes difficult. It has therefore been a problem with conventional fluid-jetting nozzle systems to assure a uniform decontamination over the entire machining area being processed.